Cathode ray tube



March 30, 1937. E w HEHLGANS 2,Q75,717

CATHODE RAY TUBE Filed May 25, 1955 Inventor Friedrich W Hehlgans,

His Attorney.

Patented Mar. 30, 1937 1 a UNITED STATES PATENT OFFICE CATHODE RAY TUBE Friedrich W. Hehlgans, Berlin-Hermsdorf, Germany, assignor to General Electric Company, a corporation of New York Application May 23, 1933, Serial No. 672,489 In Germany June 4, 1932 2 Claims. (01. 25027.5)

The present invention relates to electron dis- In Fig. l, numeral I designates a highly evaccharge tubes, more particularly to cathode ray uated or gas-containing envelope which termitubes utilized for sound recording or sound pichates at one end in a press 2 and at the other c Work end is coated on the interior with a fluorescent r, The electron tube has several advantages over substance to constitute a screen 3. Within the other known light controlling means such as are envelope there is a filamentary cathode 4 and a lamps, neon discharge lamps, or Kerr cells, when disk-like anode 5 provided with a central aperemployed for sound recording purposes. Some ture 6 for the passage of electrons on their way of these advantages are that the control of an to the screen. As is well known, positive poten- ,0 electron discharge tube is almost wholly devoid tial (not shown) may be applied between the of inertia and the amount of energy required to filament 4 and the anode 5 to give the electrons carry out the control is relatively small. sufficient velocity in order to reach and to im- Insofar as sound recording is concerned, the pact with the screen. electron tube has heretofore been employed only In accordance with the present invention,

r as a light controlling means, operating on the there is provided between the filament and the intensity principle, in which case a Wehnelt cylanode the improved combined focussing and coninder is used for controlling the intensity of the trol member which may take the form of a pair electron beam and of the light spot on the fiuorof metal plates 1, parallelly arranged to face one ent r en. another at a relatively small distance apart so An object of the present invention is to imthat the electron beam passes between them in J prove the focussing device utilized in tubes of travelling toward the anode. These plates are this general character. The improvement conelectrically connected together and may be contemplates the efiicient translation of a beam of veniently supported from the press 2 by a rigid electrons which is normally of circular configurwire 8 which may also serve as a leading-in 95 ation, or substantially so, into an elongated conductor.

H rectangular shape, or narrow strip, suitable for As shown in Fig. 2 instead of utilizing physiproducing light images on a photographic film. cally separate plates, electrically connected to- In carrying out this object, I propose to change gether, the improved focussing member 9 may be the shape of the usual type of focussing member made of one piece having an elliptical configuraordinarily provided for this purpose into a memtion or that of a flattened cylinder. In this case,

her which has a substantially elongate-d crossa lead-in wire may be taken from the member 30 sectional shape and positioned at right angles through the stem as in the case of Fig. 1. It is to the axis of the electron beam. When a focusevident that in positioning the member 9 within sing member of the improved type is utilized, the tube, the greater length of the opening in the the light spot no longer appears on the fiuormember should be in the same direction as the escent screen as a circular spot of variable direction in which it is desired that the linear 35 diameter but as a narrow strip of light whose light strip shall take. Thus the electron beam length varies in accordance with the voltage appears on the fluorescent screen as a strip of applied to the member. The light intensity of light extending in the direction of the major 40 this strip has been found to remain remarkably axis of the member. 40 constant when its length is controlled in this Fig. 3 shows another modification of the commanner. When a negative potential is applied bined control and focussing member in which the to the improved foeuss member, the l ght member is formed of two pairs of plates II], II, strip may be caused to vanish if the potential is which may either be all electrically connected tosufficiently high. The definition of the strip of gether or may be connected electrically in oppolight is the sharper, the smaller the distance besite pairs. It will be noted that the distances bea tween the oppositely disposed faces of the imtween the respective pairs of oppositely disposed proved member. plates are unequal as in the case of the modifi- The invention will be better understood when cations of Figs. 1 and 2. The light strip is thus reference is made to the drawing in which Fig. 1 given an elongated configuration atthefluorescent 50 illustrates diagrammatically a cathode ray tube screen. The sharpness of the light strip may be provided with the improved focussing and concontrolled by simply changing the potential on trol member. Fig. 2 is a perspective view of a one or the other pair of plates or by applying a modified form of the member, while Fig. 3 shows separate potential to each pair of plates. In case 5 still another modification. the potentials applied to the respective pairs of plates are different, there is no necessity of having the distances between the respective pairs of plates unequal, as obviously, the linearity of the electron beam may be obtained electrically by the difierence in the applied potentials. If desired, one of the pairs of plates may be utilized solely for control purposes whereas the other pair may be used solely for elongating the normally round spot of light into the desired linear shape.

Claims on the species of the invention shown in Fig. 3 are contained in my divisional application, Serial No. 109,712, filed November 7, 1936, and entitled Cathode ray tubes.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. A cathode ray tube containing a source of electrons, an anode, a fluorescent screen and an electrostatic control member between said source and anode for constraining the electron beam to a flat rectangular shape whereby a strip of light is produced on said screen, said control member being hollow and having a closed perimeter, said member having a substantially elongated crosssectional shape and being mounted at right angles to the axis of the electron beam.

2. A cathode ray tube containing a source of electrons, an anode, a fluorescent screen, and an electrostatic control member interposed between said source and anode for constraining the electron beam to a flat shape whereby a strip of light is produced on said screen, said control member comprising a flattened perimetrically complete cylinder.

FRIEDRICH W. HEHLGANS. 

